I'm fairly certain that when I built the first version of JS Bin I didn't know about github!
IIRC I was introduced to it as a place to host the jQuery interactive documentation (thing...) that I had updated (I've very hazy on this).
I've nearly always put my own code into the public (previously through direct links on my blog), so putting on github just seemed like the right place to put it. At the time, JS Bin was 2 PHP files.
But even today, all the payment logic is in github.
But great question. I'm pretty proud of that commit. I think sharing knowledge was the ultimate intent. It's the ethos of JS Bin too.